Wednesday, December 26, 2012

Bottom Up Design

PLACEMENT CONSTRAINTS

If you recall, when we first got into the placement window for a new component, the current constraint was listed as Automatic. It was awaiting entity selection to determine automatically which of the pre-defined constraints made the most sense. I would recommend starting off with Automatic and then adjust the constraints accordingly. In this section we will look at the pre-defined constraints that can be assumed or selected directly.

Mate

A mate takes two surfaces and points their normals towards each other and lines up both surfaces, as shown in the next figure.

Mate Offset

This is the same as a Mate except that the distance between the surfaces can be less than or greater than zero.

Align

An Align takes two surfaces and points their normals in the same direction and lines up both surfaces, as shown in the next figure.

Align Offset

This is the same as an Align except that the distance between the surfaces can be less than or greater than zero.

Orient (Parallel)

This is similar to an Align offset, except that you don’t specify the distance between the surfaces.

Insert (Coaxial)

An insert takes two cylindrical surfaces and lines up their axes, as shown in the next figure.

Tangent

A Tangent constraint takes two cylindrical surfaces, or a planar and cylindrical surface and makes them tangent to each other, as shown in the next figure.

Point on Surface

Places a datum point or vertex on a surface, as shown in the following figure.

Edge on Surface

Places a straight edge on a cylindrical or planar surface, as shown in the next figure.